Atherosclerotic plaque is commonly assessed by determining the lumen diameter of the relevant portion of the blood vessel. However, lumen diameter is a poor measure of plaque vulnerability. For example, lumen diameter provides no information about the tissue composition of the atherosclerotic plaque itself.
For robust characterization of atherosclerotic plaque, an ideal imaging device would have high spatial resolution to measure plaque morphology, offer multiple tissue classification to determine plaque composition, and be safe for serial studies. Common imaging modalities such as CT, angiography and ultrasound have not been developed to provide detailed characterization of atherosclerotic plaque. Conventional dual-energy CT would provide high resolution, but cannot provide soft tissue classification. In addition, dual-energy CT is not suitable for serial studies because it exposes the test subject to relatively high dose levels of radiation. Improved systems and methods for characterizing atherosclerotic plaques are needed.